Coating composition comprising an oxygen-containing diolefin polymer and a drying oil



United States Patent John F. McKay, deceased, late of (Zranford, Ni, by William lt l. Eliiott, administrator, Staten Island, N.Y., and Donald F. Koeneclre, Westlield, N.J., assignors to Esso Research and Engineering Company, a corporatime of Delaware No Drawing. Continuation of application Ser. No. 783,690, Dec. 36, 1958. This application May 29, 1962, Ser. No. 198,649

14- iuims. (Cl. Mil-23.7)

This application is a continuation of our prior copend ing application Serial No. 783,690, filed December 30, 1958, now abandoned.

This invention relates to an improved coating composition and improved film therefrom and more particularly to a method for increasing the impact resistance and for preventing eyeholing of an oxidized polymeric film.

The preparation of a liquid polymer of a C to C conjugated diolefin with subsequent chemical modification to incorporate oxygen in its structure is known in the art. In the past, this. oxidized polymeric oil has been applie to the surface of a material and cured to provide a film therefrom. However, it has been found that the impact resistance of the cured film is relatively poor. Therefore, a serious problem occurs in certain instances where the aforementioned characteristic is Omnipotent. Furthermore, eyeholing frequently occurs when the film has been cured by baking.

It has now been discovered that the impact resistance of the film can be substantially improved and eyeholing can be alleviated by incorporating in the oxidized polymer the combination or a conjugated drying oil and a phosphoric compound having at least one replaceable acidic hydrogen atom.

Thus in accordance with one embodiment of this invention a polymer of a C to C conjugated diolefin is prepared. The polymer is then oxidized by blowing it with air or by incorporating an unsaturated dicarboxylic acid anhydride therein. This oxidized polymer is subsequently mixed with the aforementioned phosphoric compound and drying oil to provide a coating composition. The admixture therefrom is then applied to the surface of a material, e.g., a metal plate, and cured to provide a film with increased impact resistance.

Polyrneric oils included in this invention are prepared from diolefins, particularly those which are conjugated and have 4 to 6 carbon atoms per molecule, such as butadiene, hexadiene, isoprene, dimethyl butadiene, piperylene,, and methyl pentadienc. Diolefins may be used which are copolymerized with minor amounts of ethylenically unsaturated monomers as styrene, acrylonitrile, methyl vinyl ketone, or with styrenes having alkyl groups substituted on the ring, e.g., paramethyl styrene, dimethyl styrene, etc.

A preferred diolefin polymeric oil is one prepared by reacting 75 to 100 parts of butadiene and to 0 parts of styrene in the presence of metallic sodium catalyst. Polymerization is carried out in a reaction diluent at temperatures from about 25 C. to 105 C. with about 0.5 to 5 parts of finely divided sodium per 190 parts of monomers used. The diluent used in the polymerization must boil between about -l5 C. and 200 (1., in amounts raning from 100 to 508 parts per 100 parts of monomers; preferred diluents are aliphatic hydrocarbons such as solvent naphti a or straight-run mineral spirits such as Varsol. In order to obtain a water white product, a codiluent, about 10 to parts per 100 parts of monomers, may also be used, consisting of a C to C aliphatic ether Patented July 20, 1955 or cyclic others and polyethers other than those having a OCO grouping; particularly useful ethers are dioxane 1,4 and diethyl ether. Finally, it is beneficial to use about 5 to 35 weight percent, based on sodium, of an alcohol such as methanol, isopropanol, or an amyl alcohol in order to overcome the initial induction period. resulting product may vary in viscosity from 0.15 to 20 poises. The preparation of this oil in the presence of an adrali metal or peroxide catalyst is described in US. Patents 2,762,851 and 2,586,594 which are incorporated herein by reference.

These polymeric drying oils are then oxidized by blowing them with air or oxygen, preferably in the presence of a solvent, such as aromatic solvents or solvent mixtures having a kauri-butanol value of at least 50. The choice of solvents will depend upon the oxygen content desired in the finished oil, the formation of the coating compositions, and the most economical one to achieve the desired results. Examples of suitable solvents include aromatic hydrocarbons, with or without aliphatic hydrocarbons, boiling up to about 25 0 C., preferably between 188 and 200 C. The oxidation can be carried out by blowing air or oxygen into the polymer with or without a catalyst. Suitable catalysts are organic salts of metals such as cobalt, lead, iron, and manganese. The naphthena-tes, octoates, and oleates are especially suitable. These catalysts are used in amounts ranging from 0.001% to 1.0%. The nature of the oxidized diolefin polymer largely depends upon the type of original polymerization and the extent of oxidation which is dependent upon various factors as time, temperature, catalyst, and solvent. Preferred compounds are the oxidized copolymers of to butadiene and 25 to 15% styrene with about 10 to 20% oxygen in the structure.

It is also within the purview of this invention to incorporate oxygen in the structure of a polydiolefin oil by the addition of an anhydride of an unsaturated dicarboxylic acid, e.g., maleic anhydride, chloromaleic anhydride or citraconic anhydride. However, maleic anhydride is preferred. This modification can be accomplished by adding maleic anhydride to the reactants prior to the polymerization. However, the preferred method is to add maleic anhydride to the oil after polymerization and heat the mixture therefrom at a temperature of between 50 and 250 C., preferably 180 to 220 C. for about 15 minutes to 2 hours. In accordance with this invention, it is preferred for the polymeric oil to be modified with between 0.01 and 2.5%, preferably 0.05 to 0.5% of the unsaturated anhydride, e.g., maleic anhydride. This chemical modification of the curable drying oil is described in US. Patent 2,652,342 which is also incorporated herein by reference.

In accordance with this invention it is necessary to incorporate both a conjugated drying oil and an acid phosphorus compound in the oxidized polymer to provide the improved coating composition. in the present invention, an acid phosphorus compound is defined as an acid of phosphorus or an acid derivative having at least one rcplaccaole acidic hydrogen atom. Examples of the acids are orthophosphoric acid (Hg 0 pyrophosphoric acid (H P 0 orthophosphorous (P1 1 0 and hypophosphorous acid (H PO Examples of the acid derivatives include inorganic salts such as NaH -O Na i-W0 Zn( 51 F09 inH PO r i Lfi-l PO (NH HPG and rganic esters of phosphates. However, the phosphoric acids are preferred. Furthermore, it is critical to add between 0.0l and 5 13% of phosphoric acid, preferably 9.25- 1.5% (based on weight of the oxidized polymer) or equivalent replaceable acidic hydrogen for the success of this invention. (Too high a percentage may bring about an undesirable level of oxidation inhibition.) Above this percentage excessive yellowing and gelation occurs. agitator. Complete conversion was obtained in 4.5 hours. Below this percentage the over-all effect is negligible. The catalyst was destroyed and removed from the result- In addition to the phosphoric acid, it is also necessary ing crude product and essentially all of the solvent reto incorporate 5 to 25%, preferably to 20%, of a conmoved by stripping to give a product of essentially 100% jugated drying oil in the oxidized polymeric solution. A 5 NVM. The resulting product has a viscosity of 1.5 drying oil is defined as follows: Glycerides of fat acids poises at 50% NVM in Varsol solution and the nonwhich contain two or more double bonds which absorb volatile portion thereof had a viscosity average molecuoxygen on exposure to air. Peroxides are formed which lar weight of about 8,00 9. catalyze the polymerization and as a result the oils be- A polymeric solution was then provided in a reactor come solid or semisolid and are known as drying oils. A 10 comprising 35 wt. percent of the above copolymer in conjugated drying oil is one in which the double bonds Solvesso (high percentage of aromatics with an API are in alternate positions. It should be noted that a drying gravity 30.2, a flash point of U8 (3., and a boiling range oil may be inherently conjugated, e.g., tung oil and oiticia of 322351 F.). The solution Was blown with oxygen oil; or may be formed by isomerizing a normally unconfor 2 hours and minutes at 240 F. in the presence of jugated drying oil, e.g., isomerized linseed oil and isom- 15 0.01 wt. percent of manganese as the naphthenate soap erized soybean oil; may be prepared by dehydration to as a catalyst to incorporate.10% oxygen in the structure introduce a second double bond which is conjugated, e.g., or" the copolymer. The solution with the oxidized polydehydrated castor oil. Therefore, the terminology conrner therein was stripped at a temperature of 220240 jugated drying oil is used in the art to define a general F. and a vacuum of mm. Hg to provide a product of group of compounds and each specific oil therein is with- 20 50% NVM. in the purview of this invention. These conjugated dry Various amounts of phosphoric acid (P1 1 0 coning oils are described in detail in Noller, Chemistry of jugated drying oils, and 2-ethyl hexyl alcohol were added Organic Compounds, W. B. Saunders Co. (1951), Chap to' 100 parts of the aforementioned oxidized polymeric ter II, pp. 178l84, which is incorporated herein by refersolution. Each of these admixtures was applied by spray= once. v ing a one mil coating on a polished steel plate. The coated it may also be advantageous, although not necessary, panels were subsequently cured at 350 F. for minutes to include a m'onohydric C to C alcohol, e.g., Z-ethyl to provide films A through I. The impact resistance was hexanol, n-octyl, and 2 hexanol, in the oxidized polymeric measured on a Gardner variable impact tester (rating solution to provide a smoother film. If present, the alcowith 30X magnification) as indicated in Table I. hol enerally ranges from 0 to l5%, preferably 3 to 8%, 30 AH Percentages in all examples are based on 100 Parts based on oxidized polymer by weight. of oxidized polymer.

This admixture comprising the oxidized polymer, the bl 1 conjugated drying oil, and acid phosphorus compound is the improved coating composition of this invention which Phos Ethyl Impact (inch is adaptable to provide a film with increased impact rephqrlc Drying Hexa- 1 sistance. This coating composition can be applied to the mm g gg Drymg on g g surface of a material, such as a metallic item, e.g., tin Direct Reverse plate, byany known method which, therefore, includes spraying, brushing, dipping, and the like. The thickness 25 10 of the coating can vary over a wide range but, generally, 40 1 it will be between 0.2 and 4.0 mils. The admixture, which Tungpn 10 25 has been applied to the surface, can be cured in accord- 2221; if 10 30 4 ance with any suitable method known in the art. A prew m- 0 30 4 ferred method is by baking in an oven at a temperature at r 011 (medl- 10 25 7 4 between 250 and 500 F. for 6-0 to 3 minutes, respeci5 Castor Q 30 4 a w Tuug Oil 1o 5 80 70 tivery. Other methods include inrrared baking, electronic (385mm; 15 80 70 induction baking, flame curing, air drying, curing in the (33-h presence of S0 and the like. Thus, in accordance with this invention an improved zg g l ig 3 end product has been formed. The impact resistance of y m 6 Gas Om the film has. been vastly increased. Therefore, it is now F11mS K through Werc Provided m a m marmalpossible to coat refrigerators, cans, automobiles, and F descm?i above eXcePt T1011 enamel was @corporated kitchen appliances and provide a film therefrom with the the 'OXldlZed PolyrmmJ q The Physleal Proper relatively high impact resistance which is required for ties of these films are Show In Table this use;

The following examples are submitted to illustrate and Table H not to hunt this invention. Phos: zethyl Impact (inch EXAMPLE 1 Film 233? Drying on o ii,

A butadiene-styrene drying oil was prepared from the percent percent percent Direct Reverse following charge:

Butadiene-l,3 33 g Styrene go 29 e 1 "satin-in ets: 15 s8 3% Droxane $521? ?13:21:31:1:313:31:31:: "$1? This example demonstrates that it is essential for the S success of this invention to incorporate both phosphoric 1 traight-run mineral spirits; AP-I gravity, 49.0 flash, i i e me 105 F. boiling range, 150 to 200 C.; solvent power, 33-37 acld and a Conjugated drflng 011 m the Omdlzud poly 11c kauri-butanol value (reference scale: Benzene, K.-B. Solution P v e a substan i lly imp p vagrgs; n-hepdtatne, 25.4 valuef) .10 t 50 b resistant film isperse 0 a par it: e size 0 0 microns y means of an Eppenbach homo-mixer. EXAMPLE 2 The polymerization of this charge was carried out at An oxidized polymeric solution was prepared by the 50 C. in a 2-liter autoclave provided with a mechanical same rocedure. as described in Example 1. Various amounts of phosphoric acid, conjugated drying oils, and Z-ethyl hexanol were again added to this solution. The curing and testing procedures were similar to those previously described in Example 1. The results are indicated in Table Ill.

Table III Phos- Drying 2'Ethyl Film phoric rying Oil Oil, Hexanol, Rating Acid, Per- Percent Percent cent The rating system for this example:

0No eyeholes, excellent. l-Occasional, scattered eyeholes, generally acceptable.

2Frequent eyeholes, improved but not generally acceptable.

3Control, normal eyeholing, many imperfections.

4Worse than control.

This example shows that the addition of either the phosphoric acid or the conjugated drying oil alone does not eliminate eyeholing. However, the combination of both materials does eliminate eyeholing.

Having described the general nature and embodiments of this invention, the true scope is now particularly pointed out in the appended claims.

What is claimed is:

1. A composition of matter which comprises a liquid polymer of butadiene and styrene of at least 75 wt. percent butadiene which has been air blow to incorporate from to 20% oxygen in its structure; from 0.01 to 5.0% of orthophosphoric acid; and from 5 to 25% of tung oil.

2. A composition of matter which comprises a liquid polymer of from about 75 to about 85% butadiene and from about 25 to about styrene which has been air blown to incorporate from about 10 to about oxygen in its structure, between about 10 and about 20% of a conjugated drying oil and between about 0.25 and about 1.5% of an acid phosphorus compound selected from the group consisting of an inorganic acid of phosphorus and the metallic salts thereof containing at least one replaceable acidic hydrogen therein.

3. The composition of matter according to claim 2 in which no more than about 15% of a monohydric C to C alcohol is included therein.

4. A composition of matter which comprises:

(A) a polymeric composition selected from the group consisting of (l) a liquid polymer of a C -C conjugated diolefin which has been reacted with a member of the group consisting of air and oxygen so as to incorporate between about 10 and about 20% oxygen in its structure and (2) a liquid polymer of a C -C conjugated diolefin which has been reacted with between about 0.01 and about 2.5 wt. percent of an anhydride selected from the group consisting of maleic anhydride, chlormaleic anhydride and citraconic anhydride,

(B) between about 5 and about of a conjugated drying oil and (C) between about 0.01 and about 5.0% of an acid phosphorus compound selected from the group consisting of an inorganic acid of phosphorus and the metallic salts thereof containing at least one replaceable acidic hydrogen therein.

5. The composition of matter according to claim 4 wherein the liquid polymer is the homopolymer of butadiene.

6. The composition of matter according to claim 4 wherein the liquid polymer is a copolymer of butadiene and styrene containing at least wt. percent butadiene.

7. The composition of matter according to claim 4 wherein no more than about 15 of a monohydric C -C alcohol is included therein.

8. A composition of matter which comprises (A) a liquid polymer of C C conjugated diolefin which has been reacted with a member of the group consisting of air and oxygen so as to incorporate between about 10 and about 20% oxygen in its structure, (B) between about 5 and about 25% of a conjugated drying oil and (C) between about 0.01 and about 5.0% of an acid phosphorus compound selected from the group consisting of an inorgarric acid of phosphorus and the metallic salts thereof containing at least one replaceable acidic hydrogen therein.

9. The composition of matter according to claim 8 wherein the liquid polymer is selected from the group consisting of the homopolymer of butadiene and a copolymer of butadiene and styrene containing at least 75 Wt. percent butadienc.

10. The composition of matter according to claim 8 wherein the conjugated drying oil is selected from the group consisting of tung oil, oiticia oil, isomerized linseed oil, isomerized soybean oil and dehydrated castor oil.

11. A composition of matter which comprises (A) a liquid polymer of a C -C conjugated diolefin which has been reacted with between about 0.01 and about 2.5 wt. percent of an anhydride selected from the group consisting of maleic anhydride, chlormaleic anhydride and citraconic anhydride, (B) between about 5 and about 25 of a conjugated drying oil, and (C) between about 0.01 and about 5.0% of an acid phosphorus compound selected from the group consisting of an inorganic acid of phosphorus and the metallic salts thereof containing at least one replaceable acidic hydrogen therein.

12. The composition of claim 11 wherein the liquid polymer is selected from the group consisting of the homopolymer of butadiene and a copolymer of butadiene and styrene containing at least 75 wt. percent butadiene.

13. The composition of claim 11 wherein the conjugated drying oil is selected from the group consisting of tung oil, oiticia oil, isomerized linseed oil, isomerized soybean oil and dehydrated castor oil.

14. A coating with improved impact resistance which comprises a liquid polymer of a C -C conjugated diolefin which has been air-blown to incorporate between about 10 and about 20% oxygen in its structure and which has been cured on and which is adhered to the surface of a material in the presence of between 5 and about 25 of a conjugated drying oil and between about 0.01 and about 5.0% of an acid phosphorus compound selected from the group consisting of an inorganic acid of phosphorus and the metallic salts thereof containing at least one replaceable acid hydrogen therein.

References Cited by the Examiner UNITED STATES PATENTS 2,492,124 12/49 Young et al 260-23] 2,513,389 7/50 Young et al. 26023.7 2,634,256 4/53 Sparks et al 26023.7 2,876,207 3/59 Henderson 26030.6 2,880,188 3/59 McKay 260-23.7 2,893,885 7/59 Hutchinson et a1 260-23] 3,004,937 10/61 Van Nostrand et a1. 260-851 LEON I. BERCOVITZ, Primary Examiner. DONALD E. CZAJA, Examiner. 

4. A COMPOSITION OF MATTER WHICH COMPRISES: (A) A POLYMERIC COMPOSITION SELECTED FROM THE GROUP CONSISTING OF (1) A LIQUID POLYMER OF A C4-C6 CONJUGTED DIOLEFIN WHICH HAS BEEN REACTED WITH A MEMBER OF THE GROUP CONSISTING OF AIR AND OXYGEN SO AS TO INCORPORATE BETWEEN ABOUT 10 AND ABOUT 20% OXYGEN IN ITS STRUCTURE AND (2) A LIQUID POLYMER OF A C4-C6 CONJUGATED DIOLEFIN WHICH HAS BEEN REACTED WITH BETWEEN ABOUT 0.01 AND ABOUT 2.5 WT. PERCENT OF AN ANHYDRIDE SELECTED FROM THE GROUP CONSISTING OF MALEIC ANHYDRIDE, CHLOMALEIC ANHYDRIDE AND CITRCONIC ANHYDRIDE, (B) BETWEEN ABOUT 5 AND ABOUT 25% OF A CONJUGATED DRYING OIL AND (C) BETWEEN ABOUT 0.01 AND ABOUT 5.0% OF AN ACID PHOSPHORUS COMPOUND SELECTED FROM THE GROUP CONSISTING OF AN INORGANIC ACID OF PHOSPHORUS AND THE METALLIC SALTS THEREOF CONTAINING AT LEAST ONE REPLACEABLE ACIDIC HYDROGEN THEREIN. 